“What is anxiety?” is one of the most common questions I receive from troops, veterans and military family members. That’s understandable, considering the word “anxiety” is used to refer to everything from the everyday stress associated with life to severe and unremitting post-traumatic stress.

Worry, stress, tension, nervousness, panic, fear, unease, jitters, angst and the ever-popular “heebie-jeebies” are all used to describe anxiety. However, these terms are not completely interchangeable. Although definitions vary in their complexity, anxiety is generally viewed as an unpleasant feeling of apprehension or concern. It’s a palpable feeling of unease and unrest, and often cryptic in its cause and difficult to describe.

Three similar words, however, are most often used to describe anxiety: worry, fear and stress. Worry, anxiety’s close cousin, is what we do to ourselves by thinking too much. Fear, the most primitive form of anxiety, is the emotional response to a known or suspected threat. And stress, a term used to describe just about everything psychologically and physically unpleasant, is how the body and mind feel when life’s demands are greater than what we can handle. Everything else is just a variation on these.

At times, anxiety gets an undeserved bad rap. Just like alcohol, fast food and gambling, most everything is harmless in moderation. Anxiety is no different. Actually, some anxiety can be helpful, and the “just right” amount can bring contentment.

Anxiety also improves performance, counters fatigue and motivates us to do things we would otherwise avoid. In fact, anxiety is very useful for your physical fitness test. The problem is that it’s hard to define what that “right” amount is. The amount that motivates you to perform well during a fitness test may cause someone else to blow it. So again, moderation is key.

So, when is anxiety considered a problem? It depends. Anxiety is part of our culture. It’s normal and expected. In fact, if you don’t sometimes experience at least a mild degree of anxiety, then you should probably be anxious about why you aren’t experiencing any.

A general rule of thumb is that if anxiety causes persistent and serious disruption in major areas of your life — family, work, social relationships — then it is likely a problem. It doesn’t mean that you are “sick” or “crazy”; it could mean simply that you need a little extra help dealing with life’s day-to-day hassles.

This could include talking with a mental health professional, friend, family member or chaplain or going for a walk or pumping iron at the gym.

Bret A. Moore is a clinical psychologist who served in Iraq and is the author of “Wheels Down: Adjusting to Life after Deployment.” Email kevlarforthemind@militarytimes.com. Names and identifying details will be kept confidential. This column is for informational purposes only. Readers should see a mental health professional or physician for mental health problems.